JPH07103480A - Glow plug made of ceramics - Google Patents

Abstract

PURPOSE:To provide a self current control type glow plug made of ceramics, which is provided with a stabilized strength, strong against heat shock and the like and durable against high temperature and high stress. CONSTITUTION:A pipe 2 made of ceramics is fixed to a hollow main body 1, equipped with an electrode 10, while a conductive print layer 8 is formed on the outer surface of the pipe 2 made of ceramics. One end of the pipe 2, made of ceramics, is sealed with ceramics filler 4 and a hollow part 9 is formed in the pipe 2. A tungsten wire 3 is arranged in the hollow part 9 filled with N2 gas and one end 7 of the tungsten wire 3 is connected to the conductive print layer 8 while the other end 16 of the same is connected to the electrode 10. A ceramics outer periphery coating layer 5 is formed on the outer peripheral surface 13 of the pipe 2 made of ceramics. When the tungsten wire 3 and the conductive print layer 8 are excited, the conductive print layer 8 constitutes a heat generating unit 12 while the tungsten wire 3 constitutes a current control unit 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic glow plug used in a diesel engine or the like.

[0002]

2. Description of the Related Art Heretofore, a glow plug has been constructed by embedding a tungsten W wire in a ceramic such as silicon nitride. The tungsten W wire has a resistance value of 0.1Ω and a current of 120 A at room temperature with respect to a power source of 12 V, for example. When the temperature of the glow plug rises from room temperature to 900 ° C. with the passage of time, the resistance value becomes 0.4Ω, and the current at that time is 30 A. Then, the glow plug is heated and the resistance value rises, and the resistance value becomes 1Ω and becomes stable, and the current at that time is 1
2A. That is, in the conventional glow plug used in the diesel engine, 12 is required by the controller.
When a current is supplied from a V battery, a current of 120 A initially flows, but as the temperature of the heater coil rises, the resistance value increases and becomes stable when the resistance value becomes 1Ω. Therefore, in order to stabilize the glow plug at a resistance value of 1 Ω, the current is controlled by a controller command so that the heater coil is maintained at 1 Ω.

A conventional glow plug has been developed which can be self-controlled so that the glow plug can be adjusted to 1Ω without using a controller. Tungsten W
And nickel Ni have the characteristic that the resistance value Ω increases and increases as the temperature rises. Therefore, in the tungsten W wire and the nickel Ni wire, the resistance value Ω increases as the temperature rises, the current decreases, and the current value is limited. Therefore, the self-regulating glow plug is
A tungsten W wire is embedded in a ceramic such as Si ₃ N ₄ , and a nickel Ni wire coil is connected in series with the W wire. That is, in the self-regulating glow plug, a conductor having a small electric resistance value is arranged in the heating element portion of the heater coil, and a metal wire having a large electric resistance value of the Ni wire coil is connected to the upstream side of the conductor. It was made by. In such a self-regulating glow plug, the Ni coil is overheated by passing an electric current to increase the resistance value, and the electric current is reduced to control the heat generation amount of the heating element portion of the heater coil. .

Conventionally, self-current control type glow plugs have been disclosed in Japanese Examined Patent Publication No. 4-34052 and Japanese Examined Patent Publication No. 60-194.
No. 04, JP-A-59-157423, JP-A-58-106326, and the like.

For example, in the self-control glow plug disclosed in Japanese Examined Patent Publication No. 4-34052, a current control resistor is connected in series to the heating element in order to control the temperature of the heating element at the time of heating by energization. The heating wire coil and the resistor coil are connected in series and embedded in the ceramic sintered body to form an integrated ceramic heater, and the heating wire has a temperature-resistance coefficient of 4 times or less. Such a tungsten W and rhenium Re alloy wire having a positive temperature coefficient of resistance are used, and the resistor is a wire material of pure W or pure molybdenum Mo.

The sheath glow plug disclosed in Japanese Patent Publication No. 19404/1985 directly connects the heating element and the resistor of the winding between the inner bottom of the heat-resistant bottomed metal tube and the center electrode. This is a self-regulating type sheath glow plug having the winding pitch of the resistor formed close to the central electrode side close to the electrode side fitting, and the portion close to the heating element side formed roughly.

[0007]

However, the conventional self-current control type glow plug has sufficient heat resistance, strength against heat shock, high temperature strength, etc. when used in a high temperature combustion chamber such as a heat shield engine. It was something I couldn't say. Further, in the conventionally disclosed self-regulating glow plug, a heating wire coil manufactured using a tungsten carbide wire and a resistor coil manufactured using a Ni wire coil are connected to each other, and both are made of materials having different resistance temperature coefficients. Or the heating element and the resistor of the winding are formed in different shapes, there is a problem that the Ni wire is disconnected due to overheating during use or deteriorates due to aging. The structure was complicated, and the manufacturing cost and strength were not satisfactory.

With respect to the ceramic glow plug, a self current control type glow plug can be constructed by the resistance value extremely increasing in the upstream region of the current path of the heater coil. The relationship between the resistance value and the temperature in the heater coil is expressed by the following equation. ρ _TX = ρ _{T 0} [1 + α (T _X −T ₀ )] where ρ _TX is the resistance value of the heater coil at a certain temperature T _X , ρ _{T 0} is the resistance value of the heater coil at room temperature T ₀ , and α is It is a temperature coefficient of resistance.

Normally, in a glow plug, a saturation current flows at about 1Ω at a power supply voltage of 12 V and the temperature is maintained at about 900 ° C. In order to heat the glow plug instantaneously, about 0.1Ω is required at room temperature. Usually, a heating wire, that is, a W wire used as a heater coil has a temperature coefficient of resistance of about 4 × 10 ⁻³ , so that the current cannot be saturated at 900 ° C.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and a tungsten wire coil-shaped current control unit is provided to increase the heat shield in the electrode side region and reduce the heat dissipation. A self-current control type that secures an optimum heat generation amount by adjusting the current flowing through the heat generation unit and the current control unit by configuring the heat generation unit by decreasing the heat shield degree in the tip end side region and increasing the heat dissipation amount. Provided is a ceramic glow plug which can be manufactured by arranging a tungsten wire in the hollow portion of a ceramic molded body and arranging a conductive print layer on the wall surface of the molded body and simultaneously sintering the structure. It is to be.

[0011]

In order to achieve the above object, the present invention is configured as follows. That is, the present invention is a hollow main body in which a conductor provided with an electrode is disposed in a hollow portion, a ceramic pipe fixed to the main body which constitutes a heat generating portion protruding from the main body and has a closed tip.
A conductive print layer containing tungsten powder formed on the outer surface of the pipe and the tip, a ceramics packing body that seals the end of the pipe, one end adheres to the conductive print layer and the other end fills the ceramics. A coiled tungsten wire having a coiled current controller exposed in the hollow part of the pipe and connected to the electrode through the body, and a ceramic outer peripheral coating layer covering the conductive print layer outside the pipe, The present invention relates to a ceramic glow plug, which is characterized in that

In the ceramic glow plug, the conductive print layer is spirally or entirely printed on the outer surface of the pipe.

In the ceramic glow plug, the conductive print layer contains Ni or Mo powder.

In this ceramic glow plug, the hollow portion of the pipe is filled with N ₂ gas and SiC.
The fibers are enclosed.

Further, in this ceramic glow plug, the ceramic constituting the pipe, the ceramic filling body and the ceramic outer peripheral coating layer is silicon nitride. Further, the conductive print layer has Si ₃ N
_It may also contain ₄ powders.

Further, in this ceramic glow plug, one end of the tungsten wire is arranged on a ceramic molded body forming the pipe, and a paste containing tungsten powder forming the conductive print layer is printed on the molded body. Then, the pipe, the tungsten wire, the conductive print layer and the ceramics filling body are bonded by further filling the inside of one end of the molded body with the ceramic mud-like material that constitutes the ceramics filling body and firing it. There is.

Further, in this ceramic glow plug, a polymer is used as a ceramic forming the ceramic outer peripheral coating layer on the outer periphery of the ceramic molded body forming the pipe and the paste containing tungsten powder forming the conductive printed layer. The ceramic outer peripheral coating layer is bonded to the pipe and the conductive print layer by applying a liquid material such as a precursor and baking the liquid material.

[0018]

The ceramic glow plug according to the present invention is
It is configured as described above and operates as follows. That is, in this ceramic glow plug, a ceramic pipe is fixed to a hollow main body provided with electrodes to form a heat generating portion, and a conductive print layer containing tungsten powder is formed on the outer surface of the pipe and its tip. Then, a coiled tungsten wire having a coiled current control unit is arranged in a hollow portion that seals the end portion of the pipe, and the conductive printed layer on the outside of the pipe is covered with a ceramic outer peripheral coating layer. When an electric current is applied to the wire and the conductive printed layer, the degree of heat shielding against the tungsten wire exposed in the hollow portion of the main body is large, and the conductive printed layer is opened to the outside through the ceramic outer peripheral coating layer. Therefore, the temperature of the tungsten wire becomes higher than that of the conductive print layer. Therefore, when the temperature of the tungsten wire becomes high, its resistance value becomes large, the current flowing through the tungsten wire becomes small, and the amount of heat generated from the ceramic outer peripheral coating layer is self-controlled and controlled to an optimum value. Become.

Further, in this ceramic glow plug, one end of the tungsten wire is arranged on the ceramic molded body forming the pipe, and the outer surface of the molded body is printed with a paste containing tungsten powder,
Further, a liquid material such as a polymer precursor that constitutes the ceramic outer peripheral coating layer is applied to the outer periphery of the ceramic molded body and the paste, and these are simultaneously fired, so that the conductive print layer and the tungsten are applied to the pipe. The wires are joined and the ceramic outer peripheral coating layer is joined to the pipe and the conductive print layer, so that a stable structure can be reliably and easily formed.

In particular, the tungsten wire has its coiled current control portion arranged in the hollow portion formed in the middle of the pipe, and only its both ends are connected to the ceramic filling body and the pipe, that is, another solid body. As a result, the conduction power easily raises the temperature to a high temperature, the response of self-control becomes good, and the power control becomes easy. Further, by enclosing N ₂ gas in the hollow portion, it is not necessary to consider antioxidation measures such as coating the tungsten wire with SiC or the like, and the manufacturing method is simplified and the manufacturing cost can be reduced. Further, if the conductive print layer contains Ni or Mo powder and is prepared by firing a paste, Ni or Mo has good reactivity, so that the tungsten wire and the conductive print layer adhere to each other. Sintered and good bondability.

Further, since the outer surface of the conductive printed layer is composed of the ceramic outer peripheral coating layer made of ceramics having high heat resistance, the ceramic outer peripheral coating layer constitutes a protective layer, and heat shock and heat resistance. And the high temperature strength can be enhanced.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a ceramic glow plug according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic explanatory view showing an embodiment of a ceramic glow plug according to the present invention, and FIG. 2 is a paste for forming a conductive print layer on the outer surface of a ceramic pipe pipe for producing the ceramic glow plug of FIG. It is explanatory drawing which shows the state which printed.

The ceramic glow plug is mainly composed of a hollow body 1 having a terminal or electrode 10 mounted in a hollow portion 22 with an insulator 18 such as an insulating bush interposed therebetween, a ceramic pipe 2, a tungsten wire 3 and a pipe. It is composed of a ceramics filling body 4 filled in one end of the pipe 2, a ceramics outer peripheral coating layer 5 as a protection member arranged on the outer surface of the pipe 2, and a conductive print layer 8 bonded to the outer surface of the pipe 2. The hollow main body 1 is made of a metal such as a heat-resistant alloy and has a screw 19 for attachment to other parts. Positioning fixing screw 21 is provided on electrode
Are formed. The nut 20 is screwed into the screw 21, and the electrode 10 is positioned and fixed to the hollow main body 1. Part of the ceramic pipe 2 is a hollow main body 1
The conductive print layer 8 is fixed to the inner wall surface 17 of the. In order to connect the ceramic pipe 2 to the hollow main body 1, the outer peripheral surface 13 of the ceramic pipe 2 is metalized and joined, so that the conductive printed layer 8 and the hollow main body 1 are electrically connected very strongly. Can be joined. Further, the heating portion 12 of the ceramic pipe 2 is arranged in a protruding state from the end portion 15 of the hollow main body 1. One end 16 of the tungsten wire 3 is connected to the electrode 10 via the power supply connection portion 11, and the other end 7 is inserted into the through hole 23 formed in the closed tip portion 14 of the ceramic pipe 2 to conduct electricity. The printed layer 8 is electrically connected.

In this ceramic glow plug, the hollow main body 1 has a conductor having the electrode 10 projected into the hollow portion 22, and the ceramic pipe 2 constituting the heat generating portion 12 is projected from the main body 1 to the main body. It is fixed at 1. The conductive print layer 8 containing tungsten powder is bonded to the outer surface 24 of the pipe 2. Also, pipe 2
The end on the electrode side of is sealed with a ceramics filling body 4,
A hollow portion 9 is formed in the middle portion of the pipe 2. One end 7 of the coiled tungsten wire 3 is in close contact with the conductive printed layer 8 and the other end 16 is connected to the electrode 10, and the coiled current control which constitutes a temperature control line exposed in the hollow portion 9 of the pipe 2 is controlled. It has a part 6. Furthermore, pipe 2
The outer circumference of and the outer circumference of the conductive print layer 8 outside thereof are covered with a ceramic outer peripheral coating layer 5, and the ceramic outer peripheral coating layer 5 forms a protective layer for the heat generating portion 12.

As for the conductive printed layer 8, as shown in FIG. 2, a spiral 25 is formed on the outer surface portion of the heat generating portion 12 of the pipe 2, and the outer surface portion joined to the main body 1 is entirely covered. Has been formed. In addition, the ceramic powder forming the conductive print layer 8 contains tungsten W.
In addition to the above powder, Ni or Mo powder is contained. N
Since i or Mo has good reactivity, the tungsten wire 3 and the conductive print layer 8 are adhered and sintered, the bondability becomes good, and the electrical connection is firmly formed.

Further, in this ceramic glow plug, the ceramic constituting the pipe 2, the ceramic filling body 4 and the ceramic outer peripheral coating layer 5 is silicon nitride Si ₃ N _{4 which} is rich in heat resistance and high temperature and high strength. It is a thing. Further, the tungsten wire 3 is exposed in the longitudinal direction and extends in a non-contact state with the hollow portion 9 of the ceramic pipe 2. N ₂ gas and SiC fiber are enclosed in the hollow portion 9 to prevent the tungsten wire 3 from being oxidized. Alternatively, when the inside of the hollow portion 9 is only sealed and N ₂ gas is not sealed, the tungsten wire 3 is replaced with SiC or W.
By coating with C or the like, oxidation of the tungsten wire 3 can be prevented, corrosion resistance can be improved, and durability of the tungsten wire 3 can be improved.

Further, the heating portion 12 of the ceramic pipe 2
Since the outer surface of is covered with a ceramic outer peripheral coating layer 5 of silicon nitride having high heat resistance, the ceramic constitutes a protective pipe, heat shock and heat resistance can be improved, and high temperature strength can be strengthened. Further, between the ceramic pipe 2 and the ceramic outer peripheral coating layer 5, since the spirally extending conductive printed layer 8 forms a large number of grooves 26 that spirally extend, the outer peripheral ceramic outer peripheral coating layer 5 is formed. The groove 26 is cut into the groove 26, and stable bonding strength between the ceramic pipe 2 and the ceramic outer peripheral coating layer 5 can be secured.

Next, this ceramic glow plug is
It can be manufactured by the following steps. First,
The hollow body 1 is made of a metal such as a heat resistant alloy,
Screws 19 for attaching to the hollow body 1 to other parts
Then, a screw 21 for positioning and fixing to the hollow body 1 is formed on the terminal or electrode 10. Hollow body 1
The electrode 10 is mounted in the hollow portion 22 with the insulator 18 interposed therebetween, and the nut 20 is screwed into the screw 21 to position and fix the electrode 10 to the hollow main body 1. Further, a tungsten wire 3 is manufactured by using a tungsten wire rod, one end of which is a straight end portion 7 and the other end 16 of which is a straight end portion, and the central portion of which constitutes the coil-shaped current control portion 6.

On the other hand, a cylindrical molded body having one end closed and the other end opened is prepared with a slurry of silicon nitride, that is, a slurry. A paste containing a tungsten powder, and in some cases, a mixed powder of tungsten powder and Ti or Mo powder, is printed on the outer peripheral surface of the molded body and through holes formed in the closed end of the molded body. That is, the paste is printed on the entire inner wall surface of the through hole 23 at the tip of the molded body and the outer peripheral portion which becomes the pipe 2 to be inserted into the main body 1, and the outer peripheral surface of the molded body constituting the heat generating portion 12 is It is printed spirally or on the entire surface. Therefore, one end 7 of the tungsten wire 3 is inserted into the through hole 23 at the tip of the molded body, and the straight other end 16 is arranged so as to project from the molded body.

Next, the other end of the molded body is filled with a ceramic mud-like material which constitutes the ceramic filling 4 in a state where the end 16 of the tungsten wire 3 projects. Further, a liquid material such as a polymer precursor that forms the ceramics forming the ceramics outer peripheral coating layer 5 is applied to the outer peripheral surfaces of the molded body and the paste. Therefore, the tungsten wire 3 is arranged on the molded body, the paste is printed on the outer surface of the molded body, and one end of the molded body is filled with the ceramic mud,
Further, a molded body assembly is produced by applying a ceramic mud on the outer peripheral surface of the molded body. This molded body assembly can be placed in a firing furnace and fired to obtain a sintered body forming the heat generating portion 12. Here, the end portion 16 of the tungsten wire 3 protruding from the end portion of the sintered body is connected to the power supply connection portion 11 of the electrode 10, and the outer peripheral surface 13 of the end portion of the sintered body subjected to metallization or the like is formed on the main body. The ceramic glow plug is completed by fitting and joining 1 to each other.

In this ceramic glow plug, one end of the tungsten wire 3 is arranged on the ceramic molded body, the paste is applied to the molded body, and the ceramic mud is filled inside one end of the molded body, and the molded body is molded. Since the ceramic mud is applied to the outer peripheral surface of the body and fired at the same time, the conductive print layer 8 is firmly and surely joined to the pipe 2 and the tungsten wire 3, and a good electrical connection is achieved. Moreover, the ceramic outer peripheral coating layer 5 is firmly and surely joined to the pipe 2.

Since this ceramic glow plug is constructed as described above, it operates as follows. That is, in this ceramic glow plug, when a current is applied from the electrode 10 to the tungsten wire 3, the conductive printed layer 8 and the body 1, the coiled current control section 6 of the tungsten wire 3 closes one end of the pipe 2. Moreover, since the conductive printed layer 8 is exposed in the hollow portion 9 formed by being sealed with the ceramics filling material 4 at the other end and the conductive printed layer 8 is in contact with the pipe 2, the pipe 2 is heated by the heat generated by the conductive printed layer 8. To be done. Here, the heat generated in the conductive print layer 8 is radiated through the ceramic outer peripheral coating layer 5, but the heat generated in the coil-shaped current control unit 6 of the tungsten wire 3 is not radiated, and the coil-shaped current control unit 6 is not radiated. Is a conductive print layer 8
Extremely high temperature compared to. When the temperature of the coil-shaped current control unit 6 becomes high, its resistance increases and becomes large, and the current flowing through the tungsten wire 3 is suppressed and becomes small, so that the heat generation amount of the heat generation unit 12 is self-controlled. Further, when the temperature of the tungsten wire 3 is lowered, a current again flows through the tungsten wire 3 to heat the heat generating portion 12 by the conductive print layer 8, so that the heat generating portion 12 is always maintained at the optimum heat generation amount.

In this ceramic glow plug, since the pipe 2 in which the conductive print layer 8 is embedded is exposed to the outside of the combustion chamber or the like, heat is dissipated from the pipe 2 and, for example, the temperature of the heat generating portion 12 is 900 ° C. The resistance value of the conductive printed layer 8 becomes 0.4Ω, but the temperature of the tungsten wire 3 is 1800 ° C. because the tungsten wire 3 is located in the sealed hollow portion 9 and is shielded from heat. Then, the resistance value of the tungsten wire 3 becomes 0.6Ω. Therefore, in this ceramic glow plug, the total sum of the resistance values of the tungsten wire 3 and the conductive print layer 8 is 1Ω, and the stable state is achieved.

[0034]

The ceramic glow plug according to the present invention is constructed as described above and has the following effects. That is, in this ceramic glow plug, a ceramic pipe constituting a heat generating portion is fixed to a hollow main body having electrodes, a conductive print layer is formed on the outer surface of the pipe, and both ends of the pipe are Since the other end of the closed end is sealed with a ceramics filler and the coiled tungsten wire is exposed in the hollow portion of the pipe, when the tungsten wire and the conductive print layer are energized, the tungsten wire is The temperature becomes extremely higher than that of the conductive print layer, the tungsten wire constitutes a temperature control line, and the amount of heat generated from the ceramic outer peripheral coating layer is self-controlled and controlled to an optimum value.

With this structure, the glow plug made of ceramic has a printed thin film on the outer circumference of the tubular pipe, and the thin film forms a conductive printed layer. When the conductive printed layer is energized, The conductive print layer generates heat, the pipe constitutes a heat generating portion, and the temperature of the entire pipe rises uniformly. Furthermore, since the end of the tungsten wire that is in close contact with the through hole of the pipe is baked in the presence of the paste, the conductivity of the connection between the conductive print layer and the tungsten wire is extremely good. In addition, if the conductive print layer contains powder of titanium Ti or molybdenum Mo in addition to tungsten powder, the bondability is further improved.

Further, this ceramic glow plug is
A paste of tungsten powder was spirally printed on the outer surface of the molded body of silicon nitride, a tungsten wire was attached to the molded body, and the outside of the paste of tungsten powder was coated with a muddy product of silicon nitride to form the molded body. So
The heating coil can be easily formed on the outer peripheral surface of the pipe, and the firing is easy, and the electrical connection is surely achieved. Alternatively, a tungsten powder paste may be printed on the entire outer surface of the molded body.

In this ceramic glow plug, the heat resistance, high temperature pore strength and durability are improved by making the pipe, the ceramics filling body and the ceramics forming the ceramics outer peripheral coating layer of silicon nitride. be able to. Further, by including powder of Si ₃ N _{4 in} the conductive print layer,
It is possible to enhance the bonding strength between the conductive print layer and the ceramic outer peripheral coating layer.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a ceramic glow plug according to the present invention.

FIG. 2 is an explanatory diagram showing a state in which a paste forming a conductive print layer is printed on the outer surface of a ceramic pipe in the ceramic glow plug of FIG.

[Explanation of symbols]

 1 Hollow Body 2 Ceramic Pipe 3 Tungsten Wire 4 Ceramics Filler 5 Ceramics Outer Cover Layer 6 Coil Current Control Section 7, 16 Tungsten Wire End 8 Conductive Print Layer 9 Hollow Section 10 Electrode

Claims (8)

[Claims] 1. A hollow main body in which a conductor provided with an electrode is arranged in a hollow portion, a ceramic pipe fixed to the main body which projects from the main body to constitute a heat generating portion and has a closed end. A conductive print layer containing tungsten powder formed on the outer surface of the pipe and the tip, a ceramics packing body in which the end of the pipe is sealed, one end of which is adhered to the conductive printing layer and the other end of which is the ceramics packing. From a coil-shaped tungsten wire having a coil-shaped current control portion exposed in the hollow part of the pipe and connected to the electrode through the ceramic outer peripheral coating layer covering the conductive printed layer on the outside of the pipe, Ceramic glow plug characterized by being configured. 2. The ceramic glow plug according to claim 1, wherein the conductive printed layer is spirally or entirely printed on the outer surface of the pipe. 3. The ceramic glow plug according to claim 1, wherein the conductive print layer contains Ni or Mo powder. 4. The ceramic glow plug according to claim 1, wherein N ₂ gas and SiC fiber are enclosed in the hollow portion of the pipe. 5. The ceramic glow plug according to claim 1, wherein the ceramic constituting the pipe, the ceramic filling body, and the ceramic outer peripheral coating layer is silicon nitride. 6. The ceramic glow plug according to claim 5, wherein the conductive print layer contains Si ₃ N ₄ powder. 7. The ceramic wire forming the pipe is provided with one end of the tungsten wire, a paste containing tungsten powder forming the conductive print layer is printed on the green body, and the green body is further formed. The pipe, the tungsten wire, the conductive print layer, and the ceramics filling body are joined by filling the inside of one end with a ceramics sludge forming the ceramics filling body and firing it. Item 2. A ceramic glow plug according to Item 1. 8. A liquid material such as a polymer precursor forming a ceramic forming the ceramic outer peripheral coating layer on the outer periphery of a ceramic molded body forming the pipe and a paste containing tungsten powder forming the conductive print layer. The ceramic glow plug according to claim 7, wherein the ceramic outer peripheral coating layer is bonded to the pipe and the conductive print layer by applying and firing.